Although there is remarkable species diversity in the ocean, especially in warm temperate and tropical coastal waters, many black boxes exist in the evolutionary processes and mechanisms of such enormous biodiversity. There are few obvious physical barriers in the ocean, and dispersal is extensive during the early life stage of organisms, reducing opportunities for allopatric speciation. Marine speciation follows similar processes to terrestrial ecosystems but is not the same: opportunities for allopatric isolation are fewer in marine environments, leaving greater opportunities for speciation along ecological boundaries and niches.
Anemonefishes are an iconic group of tropical reef fishes well-known for their mutualistic interaction with host sea anemones. This group is considered a notable example of marine adaptive radiation caused by the evolution of the symbiosis with sea anemones as the key innovation and subsequent rapid ecological niche divergence linked with host and habitat use. They have recently emerged as a new model organism for marine adaptive radiation. Anemonefishes show notable ecological divergence, including variation in host specificity. In addition, there is remarkable divergence in various ecomorphological traits and behavior traits, possibly associated with adaptation to their ecological niches. What is the genetic basis for this phenotypic adaptive diversification? The evolution of gene regulation and expression between species frequently contributes to adaptation. At least some components of morphological and behavioral evolution are likely associated with cis-regulatory changes.
Therefore, we first explored the pattern of genome-wide allele-specific expression using F1 hybrid individuals between host generalist (Amphiprion clarkii) and specialist (A. ocellaris) anemonefish species whose phenotypic traits differ extremely. In this presentation, we introduce the landscape of cis-regulatory divergence between the generalist and specialist species.